For sterile collection, it is necessary to collect samples for testing and monitor for any microbial contamination. Microorganisms, such as Listeria monocytogenes, can reside in biofilms, or have strong attachments to industrial surfaces that afford protection to these types of pathogenic or disease-causing microorganisms from sanitizing agents, competition from other microorganisms, mechanical removal, and environmental stressors, such as drying or UV exposure.
Food manufacturers have a need to continuously monitor and collect samples, particularly in production areas, in order to avoid outbreaks or to produce food products with little to no microbial contamination. It is commonly known that pathogenic microorganisms in the production environment may contribute to contamination of the food products being produced. Consequently, surfaces in the production areas where samples are routinely collected include ceilings, floors, walls, drains, and equipment. Improper or incomplete sampling of a surface may lead to inaccurate and false results for microbial safety in the production environment and potentially result in contamination of the food products during production.
It is crucial that the device for collecting samples be robust and durable to avoid any mishap that could stop or delay production. A mishap can easily occur if the device for collecting samples, or a portion of the collection device, breaks in hard-to-reach areas or is inadvertently dropped into a cooking vessel or a storage tank. Similarly, if the collection device breaks or fragments during sample collection, pieces of the collection device can easily enter the food during production. Furthermore, an improperly designed collection device could become wedged or caught in hard-to-reach areas of production equipment, and removal could require disassembling the production equipment.
Typically, the device for collecting samples has a swab of absorbent material attached on the distal portion of the device that is rubbed onto or scrubbed against a sampling surface for collecting the sample. Such swabs of cotton, dacron, alginate, or foam on a swab stick handle made of wood or plastic are commonly used to collect the sample. After collecting the sample, the swab is placed into a sterile test tube or a collection bag for later testing and processing. The swabs are normally suited for small clinical sampling surface areas such as the throat, while industrial sampling surfaces require stronger and bigger collection devices. The swab may be effective in accessing hard-to-reach areas because of its thin profile, however, it is inefficient when sampling a larger industrial area such as a conveyor belt or floor. Further, the user collecting the sample is required to press down firmly and to scrub the surfaces of a food production area to disrupt biofilms that are formed by microorganisms. A failure to disrupt and collect a biofilm during sampling can result in a false negative determination. The swabs may easily break when rubbing and lifting the biofilm to obtain a good sample from an industrial surface.
Sometimes a sponge is held directly by the user in collecting a sample. Direct handling of pre-moistened sponges is described in the U.S. Department of Agriculture (USDA) methods for sampling and testing cattle carcasses for Salmonella and Escherichia coli. However, these sponges are susceptible to mishandling by the user, resulting in contamination of the sample and inaccurate results. The user may easily contaminate the sample by touching the sponge.
Alternative swab devices have been developed for collection of samples, such as the device described in U.S. Pat. No. 6,383,804, wherein a sampling device with a snap-off head includes an elongate handle, a paddle head, and an absorbent material that wraps around the paddle head. A score line is included between the paddle head and the elongate handle that allows the user to snap off the paddle head from the elongate handle. The disadvantage of this design is that while the sampling device with a thicker wall of plastic at the score line can withstand greater force when the user presses on the sampling device, the greater wall thickness at the score line makes it difficult to break away the head away from the handle after the sample is collected. On the other hand, a thinner wall at the score line makes the paddle head susceptible to breaking away the paddle head from the handle while the sample is being collected if the user presses hard on the surface to disrupt the biofilm. Consequently, the design is not desirable since it is imperative that the score line thickness be precisely accurate to avoid inadvertent breakage during sampling while maintaining sufficient durability to remain intact when the user presses and scrubs against the surface for sampling.
The other disadvantage of the sampling device with a snap-off head is that the absorbent material is affixed to the paddle head using an adhesive or sonic welding between the absorbent material to the plastic portion of the paddle head. Bonds between absorbent materials and the plastic used for the paddle head are typically weak. Therefore, the sponge may easily detach from the plastic paddle head during sampling or rubbing against rough surfaces.
Therefore, the ideal device for collecting and sampling should be durable and strong enough to withstand the pressure applied by the user pressing on the collection device without breaking or snapping off from the handle. The ideal collection device would be designed in a way that the device can be easily inserted into a hard-to-reach area with minimal concern that it will be caught or that portions of the device will be left behind after the sample is collected. The ideal collection device would be designed and constructed in a manner that resists breakage, yet affords sufficient flexibility to collect samples around a bend or corner in production equipment. Moreover, the collection device would be easy to use and present minimal opportunity for the collection device to get caught in equipment when collecting samples. The ideal collection device further would be effective in collecting from rough and/or wide surfaces such as concrete floors or evaporation coil fins in refrigeration units without the absorbent material abrading and tearing away from the handle. The ideal collection device would be capable of easily detaching from the handle without the need for the user to touch the sample, in order to prevent contamination. The ideal collection device would be modular to accommodate different sizes of paddle heads for providing flexibility in use.
The present invention incorporates a design in which the absorbent material used for collection is directly bonded to itself. The strongest bonds and the greatest flexibility in the choice of adhesives are obtained when the adhesive can be applied to two areas of the same material. Bonding of the absorbent material to itself strongly affixes the absorbent to the sampling device to withstand the pressure applied by the user during sampling. The present invention is directed to fulfilling all of these needs and others as described below.